Table of Contents

EPD Surface Samples

On this page: An introduction to pollen surface samples

Introduction

The EPD now includes modern pollen surface samples in their own database, the EMPD

The development of publicly-accessible databases of fossil pollen data in the last 20 years such as the European Pollen Database (EPD) (http://www.europeanpollendatabase.net/), have provided scientists with an unrivalled source of information to study past changes in terrestrial vegetation, land-cover and climate at large spatial scales over the Quaternary period. Interpreting this fossil pollen record however requires a clear understanding of the relationship between pollen as the proxy, and the environmental parameter (vegetation, land-cover, climate) that the pollen proxy represents. Understanding this relationship has largely been achieved through the use of modern pollen surface samples.

There is a pressing need from the European scientific community for a standardised, fully documented and quality-controlled dataset of modern pollen samples which can be openly accessed, and to which scientists can also contribute and help maintain. After a major community based effort starting in 2011 we have now established a modern surface sample database within the EPD that contains almost 5000 samples. The European Modern Pollen Database (EMPD) is now available and free to download.

The first stage of the database resulted in a publication co-authored by all participants Davis et al. 2013. Please note the additional Erratum which provides some important corrections, particularly to the official author list.

We are now attempting a second stage of expansion to further increase the size of the EMPD

Following the EPD Open Meeting at CEREGE, France in June 2016, it has been decided to build on the success of the EMPD by initiating a second stage of expansion. We are therefore again encouraging European palynologists to submit their modern surface samples to the database. More details are on the EMPD stage 2 page.

Why are pollen surface samples useful?

Surface samples have been widely used to study past vegetation, land-cover and climate

2) Integration with vegetation models. A growing realisation of the link between the climate system and the terrestrial biosphere has seen the development of vegetation models and their integration with the pollen record of past vegetation change. This has been based on the concept of compatible units based on Biomes and Plant Functional Types (or Traits) developed within projects such as BIOME6000 (Prentice et al 2000), that have been evaluated using surface pollen samples over the European region (Prentice et al 1996, Roberts etc) and the Former Soviet Union (Tarasov et al 1998, Mokhova et al 2009). Surface samples have also been used to develop and refine these techniques in a number of other European studies, including the relationship between plant traits and climate (Barboni et al 2004), and the probabilistic assignment of plant attributes and biomes (Gachet et al 2003, Gritti et al 2004). A different but related application of surface samples has also been to evaluate the ability of niche-models to reconstruct past changes in the distribution of individual plant taxa in response to climate change (Pearman et al 2008).

4) Quantitative estimates of past (anthropogenic) land-cover. Vegetation models provide quantitative reconstructions of land cover, but reconstructions of land cover from pollen data is subject to bias associated with differences in pollen productivity between taxa and differences in size of source area between different pollen sites. Pollen surface samples have been essential in developing techniques to allow us to correct for this bias in projects such as POLANDCAL (Gaillard et al 2008), and the ongoing LANDCLIM project (Soepboer et al 2007, Gaillard et al 2010, Hellman et al 2008). They have also been used together with satellite-derived estimates of woodland vegetation cover to quantify past changes in woodland cover from fossil pollen data (Tarasov et al 2007).

5) Delimitation of forest boundaries. Altitudinal and latitudinal changes in forest boundaries have often been interpreted in the fossil pollen record as a proxy for climate change. The free dispersal of pollen either side of this boundary make defining this limit from the pollen record difficult. Pollen surface samples, often together with macrofossils, have been used to investigate this problem in areas such as the forest-steppe boundary (Tarasov et al 1998, Djamali et al 2009), forest-tundra boundary (Gervais & MacDonald 2001), steppe-forest-tundra boundaries (Pelánková et al 2008, Pelánková & Chytry 2009) and the mountain timberline (Conner et al
2004).

A brief history of surface sample datasets

Here are some examples of the main surface sample datasets for Europe that have been used in the past:

Huntley & Prentice 1988

The pioneering pollen-climate reconstruction of Huntley & Birks (1988) used core top samples from Huntley & Birks (1983) Atlas of Past and Present Pollen Maps for Europe 0-13000 Years. These were mainly digitised from published diagrams.

Huntley 1990

The same digitised Huntley & Prentice (1988) dataset was also used in later studies.

This study used a combination of Huntley & Birks (1983) digitised data, plus other core top samples from the newly established EPD.

Cheddadi et al 1998

The climate reconstruction for the site of Tigalmamine in Morocco used raw count surface sample data from Morocco, Spain and Italy as also used in Prentice et al 1996.

Barboni et al 2004

This study used only raw count data, compiled from a variety of sources, including EPD core tops, surface samples as shown in Prentice et al 1996, plus additional surface samples from individual contributors. Note that this location map is not shown in the publication.

Feurdean et al 2008

The large dataset used in this study is a combination of Prentice et al (1996) (digitised data) with additional data from Peyron et al (1998), Klotz (1999) and Klotz et al (2003).

Bordon et al 2009

Perhaps the largest dataset of raw pollen counts has been compiled by Odile Peyron and colleagues, which includes a core of raw count data used in earlier studies, plus additional data from throughout Eurasia.

Problems with existing datasets

Existing datasets of European surface pollen data have been compiled by individuals and research groups for specific research purposes and contain a number of significant problems, not least the fact that they are often poorly documented and therefore difficult to audit. The large datasets of Guiot (eg Prentice et al 1996, Feurdean et al 2008) and Huntley (eg Prentice et al 1996, Allen et al 2002, 2009) both contain large amounts of percentage data digitised by hand from published pollen diagrams that are based on non-standardised pollen sums, often including only select taxa, and subject to digitisation errors. Much of this includes old core-top data collected by Huntley & Birks (1983), which includes sites with poor dating control. Even where this older percentage data has been removed, errors have been identified including duplicate samples, errant geo-referencing (often in conversion from analogue or UTM to decimal) and poor sample selection (for instance core top samples selected on the basis of sample number, not age). Even in the best available datasets meta-data is incomplete so that many important details are missing, such as information about the site/sample, sampling method, and geophysical data. There are also many areas of Europe that are simply not represented in these datasets.

Gervais, B.R., MacDonald, G.M., 2001. Modern pollen and stomate deposition in lake surface sediments from across the treeline on the Kola Peninsula, Russia. Review of Palaeobotany and Palynology 114, 223-237.

Huntley, B., 1993. The Use of Climate Response Surfaces to Reconstruct Paleoclimate from Quaternary Pollen and Plant Macrofossil Data. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 341, 215-223.